alt Hacker NewsThere's definitely one code change that's needed - you need to override the Allocator being used by standard library containers (or, live without standard library containers) and by any third-party dependencies you have. That feature is not even stable, let alone idiomatic.
Using the allocator interface is only required if you allocate, which in this context you explicitly don't. If you want to use static preallocated memory in Rust, you'd have to use #[no_std] and only have access to the core part of the standard library. On the plus side, this is a very well supported and stable configuration, the core library is still pretty rich, and there's plenty of no_std libraries to choose from in the ecosystem.
I used "most" in the pedantic sense of "just a little bit over 50% if you count individual lines and not whole libraries". Most code doesn't operate on Box, Vec, String etc. directly, and is happy with & and &mut to underlying data. And even when it does, it's usually used for giving static lifetime to data, which is a non-issue here because all your preallocated memory has static lifetime already.